AB0138 XANTHINE OXIDOREDUCTASE: BLOOD PROFILE IN SYSTEMIC CONNECTIVE TISSUE DISEASES
Authors: E. Mozgovaya, S. Bedina, A. Trofimenko, M. Mamus, S. Spitsina, I. Zborovskaya
Journal: Annals of the Rheumatic Diseases (2022)

Background Systemic lupus erythematosus (SLE) and systemic scleroderma (SSc) are systemic connective tissue diseases. Their development is based on a generalized immune inflammatory process. Deep immunological and metabolic disorders in these diseases have along with general characteristic distinctive features. XOR is a multifunctional enzyme. The reactions catalyzed by XOR are a source of reactive forms of oxygen and nitrogen, nitric oxide, which are of great physiological importance, and are also responsible for the development of many pathophysiological reactions. Analysis of changes in the activity of interconverting forms of XOR (xanthine oxidase (XO), ЕС 1.17.3.2 and xanthine dehydrogenase (XDG), ЕС 1.17.1.4) in plasma and blood cells is of interest. Objectives to characterize differences of XO and XDG activities profiles in blood of SLE and SSc patients. Methods The researcher was carried out in agreement with the WMA Declaration of Helsinki principles. 56 SLE patients and 51 SSc patients were enrolled in this study. Diagnosis of SLE was verified using the SLICC criteria (2012). SSc was verified according to ACR/EULAR criteria (2013). The reference group consisted of 35 healthy controls. XO and XDG activities were measured in plasma, lysed WBC, lysed RBC using spectrophotometric method [1]. Results were expressed as Me (Q 25 ; Q 75 ). The Mann-Whitney U test was used for statistical analysis, differences were considered significant when p&lt;0.05. Results Mean age of SLE patients was 35 (31; 42) years, mean duration of disease was 8 (5; 11) years. Mean age of SSc patients was 43 (38; 48) years, mean SSc duration was 8 (6; 9) years. The enzyme indices included in the study did not depend on the sex and age of healthy individuals. XO activity was increased in plasma of SLE and SSc patients (p&lt;0.001 for both disease). The activity of XO was higher in SLE (p&lt;0.001). XO activity of lysed WBC was decreased in both diseases (p&lt;0.001). XDG activity was decreased in lysed WBC and lysed RBC of patients with SLE and SSc (all p&lt;0.001). Activity of this enzyme was lower in lysed WBC and higher in lysed RBC in SLE compared with SSc (all p&lt;0.001). In contrast to SLE, accompanied by low levels of plasma XDH activity (p&lt;0.001), SSc was characterized by increased activity of this enzyme (p&lt;0.001). Also, increased XO activity was revealed in lysed RBC of SSc patients (p&lt;0.001). The values of this enzymatic activity did not differ between the group of SLE patients and healthy controls (p=0.977). Conclusion Changes in the activity of oxidase and dehydrogenase forms of XOR were revealed in plasma, lysed WBC, lysed RBC of SLE and SSc patients, which determine characteristic blood profiles in these diseases. Changes in the balance of XOR enzymatic activities can affect the exchange of purine nucleotides, the pool of reactive oxygen and nitrogen species in body tissues, participating in the processes inherent in these diseases. References [1]Mozgovaya E.E. et al. Siberian Journal of Life Sciences and Agriculture 2021;3:288-304. Disclosure of Interests None declared